Did the Herrero genocide happen in this timeline?In what way is it an analog to the Second Boer War? In that one, Britain had problems fighting a small force of men who had switched to a bloody insurgency, true, but unlike the CSA, Britain was this massive Great Power that was somehow getting bloodied in what was supposed to be a small police action in its own colony. It also exposed weaknesses in British military doctrine and forced the British Empire to modernize its army properly and seek allies on the global stage. The CSA isn't a major power, and while Haitian resistance is surprising, the CSA's humiliation isn't that big a deal. It's a response to getting smacked down by Spain, sure, but Spain was generally regarded as a European power, even if it's in pretty bad shape these days.
If you mean "the war that introduced the horrible, horrible concept of the concentration camp", then yeah, you're probably right. Although one can argue the Herrero genocide carried out by the Germans precedes this as a wide-scale act of ethnic cleansing.